Letter to the Editor
Ringworm in sows
"Ringworm in lactating sows" by Pittman and Roberts1 was an outstanding example of an article that provides the swine practitioner with excellent science and clinical observations. This type of case report in JSHAP is an outstanding contribution to our profession's knowledge base. By presenting clinical conditions seen frequently in practice, the whole profession benefits when swine practitioners present and review what is known and what is not. In addition, the pictures were outstanding!
As a swine practitioner, I saw a lot of ringworm in sows in the 1980s. The interesting thing was that it always occurred under the same conditions. A lot of our clients at that time had sow gestation outside with modern indoor farrowing houses. As soon as the sows came inside to farrow, the lesions associated with ringworm in sows were immediately seen just as the pictures in the article showed. A few interesting things that we noticed:
Ringworm in pigs is quite different from ringworm in other species in that there is no loss of hair and the animals do not scratch.
Instead of the young developing ringworm, as in puppies, calves, and kittens, the spread of ringworm from the sows to the pigs was never seen. Do not confuse the lesions of pityriasis rosea in farrowing and nursery piglets with ringworm.
When the sows were sent back outside into gestation, the lesions disappeared within 1 to 2 weeks. It was always thought that sunlight played a role in this. In the middle to late '80s and into the '90s, as indoor gestation was built, we wondered if ringworm would continue to be an ongoing problem in the sow herd. This did not appear to be the case. In fact, it is very rare now to see ringworm in sows at all. It makes one wonder if there has been some immune change in the status of our sows as we have taken them inside that has helped eliminate this problem.
The sow herds that had the absolute worst lesions were almost always very productive units weaning a lot of pigs.
Keep up the good work in including peer-reviewed case reports such as this in our journal.
-- Larry Rueff, DVM Greensburg, Indiana
1. Pittman JS, Roberts JD. Ringworm in lactating sows. J Swine Health Prod. 2005;13:86-90.